Is it possible to not return any data when using a GraphQL mutation?

I have several GraphQL queries and mutations, now I'm trying to implement a delete mutation without returning any data:

    type Mutation{
addElement(element: ElementData): ID
removeElement(id: ID): ¿?
}

However, it seems to be required to have a return value for the delete operation. Is there a way to perform an "empty" response in GraphQL? I would like to avoid things like returning a boolean or status flag if possible.

I'm not sure on what are the best practices for GraphQL delete operations.

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According to this Github issue you cannot return nothing.

You can define a return type which is nullable e.g.

type Mutation {
addElement(element: ElementData): ID
removeElement(id: ID): Boolean
}

But I suggest you return the id of the deleted element, because if you want to work with a cached store you have to update the store when the delete mutation has ran successfully.

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最佳答案

(A) Solution with graphql-scalars

The original answer is below.

Here is another one solution with graphql-scalars library:

  1. install npm install graphql-scalars and then
  2. import their Void type: https://www.graphql-scalars.dev/docs/scalars/void

(B) Solution with a custom scalar

Note: design with void-result from mutations goes against "GQL best practices"

This example was written for NodeJS Apollo Framework, but it is pretty easy to convert the implementation for your language/framework

I'm pretty sure: there is an NPM-package named graphql-void but if you don't want to add another one dependency just copy this code.

1. define Void-scalar in your schema

# file: ./schema.gql


scalar Void

2. implement resolver

// file ./scalar-void.js


import { GraphQLScalarType } from 'graphql'


const Void = new GraphQLScalarType({
name: 'Void',


description: 'Represents NULL values',


serialize() {
return null
},


parseValue() {
return null
},


parseLiteral() {
return null
}
})
export Void

3. add the resolver to ApolloServer

Add the Void resolver to the options of your instance of Apollo Server:

# file: ./server.js


import { ApolloServer } from 'apollo-server-express'
import { Void } from './scalar-void'


const server = new ApolloServer({
typeDefs,  // use your schema
resolvers: {
Void: Void,
// ... your resolvers
},
    

})

4. use Void for your mutations in the schema

Finally, use the new scalar in your schema:

# file: ./schema.gql


type Mutation{
addElement(element: ElementData): ID
removeElement(id: ID): Void
}
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If you use TypeScript and graphql-codegen:

  • In the GraphQL schema:

    scalar Void


type Mutation {
removeElement(id: ID): Void
}

  • In the codegen config for resolvers:

    config:
scalars:
Void: "void"

With this config TypeScript will ensure that nothing is returned from the removeElement mutation resolver. And the returning value for the mutation will always be null on the GraphQL side.

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Check out graphql-scalars Void. This is standard boilerplate for all of my GraphQL projects.

npm i graphql-scalars

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